Image: TfLNewly released correspondence has revealed how designer Thomas Heatherwick personally urged action to tackle complaints of “stifling” heat on the New Routemaster bus after passengers lobbied him direct about the issue, causing concern that his studio’s reputation could be damaged by its association with the vehicle.

One of the true “flagship” schemes of out-going Mayor Boris Johnson’s time at City Hall, the Heatherwick-designed buses entered full passenger service in 2013.

Initial reaction was positive with many passengers praising the return of rear platform, hop-on/hop-off boarding to London’s bus network.

However rising summer temperatures soon prompted complaints about “uncomfortable” levels of heat which many suspected was caused by the decision not to include opening windows and to instead rely on an internal cooling system to regulate temperatures.

With a project so personally associated with the mayor generating sustained criticism, bosses at Transport for London sought to downplay the complaints and resulting media coverage.

Former transport commissioner Sir Peter Hendy repeatedly insisted the New Routemasters were “no hotter than any other bus” and claimed that “the new bus, when the cooling is working properly, is cooler than the equivalent latest ordinary bus.”

Sir Peter also told the BBC that it was “a folk myth” to suggest the vehicles were hotter than traditional designs.

TfL’s public comments were matched by strong resistance to suggestions made by City Hall that the agency consider fitting opening windows to avoid further negative headlines.

With complaints resurfacing the following year the organisation sought to suggest that some of those behind the gripes were motivated by a dislike of, or political opposition to, the mayor.

However a letter sent by Mr Heatherwick to Leon Daniels, TfL’s head of surface transport, in September 2014 and released to this site under Freedom of Information laws rejected this assessment.

The award-winning designer told Daniels that the level of complaints, which included “a number of irate calls to my studio” meant it was “clear that this has not been about Boris-bashing.”

“Travellers are simply too hot and uncomfortable in our busses in the hot months of the summer.”

He added: “There was a similar level of negative discourse last year and no prospect of any let up in future summers throughout the life of the busses.”

Heatherwick expressed concern that “public perception for accountability swings from TfL to Wrightbus, but ultimately to Heatherwick Studio and myself, as it is mostly seen as a design issue.”

Although Hendy had put out a statement the previous summer clarifying that it was TfL’s decision not to include opening windows, Mr Heatherwick said “this perception has not lasted.”

The designer’s letter said “a significant part of the problem is psychological,” adding that “without the ability to open a window [passengers] feel claustrophobic at their inability to get a gust of fresh air.”

Mr Heatherwick said adding “a few opening windows would help passengers experience the heat as an inevitable product of the weather” rather than believing it was “being forced on them by the busses’ poor design.”

While Heatherwick was keen not to be publicly “at odds with TfL” he stressed that his studio “is dependent on its reputation for the excellence of its design” and so it was important that the issue be addressed either by the fitting of a more powerful cooling system or revisiting the window design.

In a response sent three weeks later, and only after Heatherwick’s office had chased for an answer, Daniels suggested that a “workshop” consisting of members of Heatherwick’s team, TfL and Wrights be assembled to “look against at both the options.”

TfL emails sent in January 2015 to an external contractor confirmed the agency were “looking at improved air volumes and circulation, we are also looking at opening windows and improved Engine bay insulation to reduce radiated heat into the lower saloon.”

However by April no final decision on how to address the complaints had been reached, prompting Heatherwick’s office to raise additional concerns with TfL.

On April 28th his executive assistant contacted Mike Weston, head of buses at TfL, saying Heatherwick was “concerned that there seems to have been no apparent action and feels that it is really important that we find a way to solve this, especially with summer coming.”

The email also raised concern that the issue was beginning to impact on Heatherwick’s public appearances, with the sender writing:

“The other thing that is currently happening is that Thomas is giving public talks and people are starting questions about it again and those questions (criticisms) are bound to increase and likely be much worse than last year given that it has not been resolved. How should he respond to people’s questions and what action can he say is happening?”

Despite the constant public complaints, Heatherwick’s own urging of action and growing political pressure to resolve the issue before Mr Johnson stepped down as mayor, TfL took a further six months to confirm that windows would be retrofitted to all existing buses at an estimated £2m cost to the taxpayer.